Your bike helmet may be the most important bit of cycling kit you own, but is
it really worth spending hundreds of pounds to get a top-of-the-range model,
asks Matthew Sparkes

If you watched the brutal fifth stage of the Tour de France last month you saw Bell's new aero helmet atop the noggin of Team Belkin's grimacing, mud-encrusted Lars Boom as he crossed the finish line victorious and completely, utterly spent.

The bright green team was the only one sporting the Star Pro this year and that heroic image will no doubt be worth its weight in gold to Bell's marketing team. But when it goes on sale in November, for the best part of £200, should you buy one? Is it really for us mere mortals?

One of the problems with designing helmets is that you can have a fast, aerodynamic shape or you can have a comfortable, cool one with plenty of air vents. Ideally you’d have both, but the laws of physics won’t have any of it.

To get around this, Bell has designed a nifty mechanism that allows you to open and close several vents with a single switch. If you're sitting in the peloton on a baking hot day you can have them open to let a cooling whoosh pass over your head, but if you're gritting your teeth and going for a sprint you can slam them shut and save a few watts.

It’s all rather clever, but during a baking weekend in the Pyrenees I found that it got a little sticky after a few dozen uses, leaving me with the option of closed vents or nearly - but not quite totally - open vents. Not ideal.

Bell tested the Star Pro in a wind tunnel at 25mph with various sidewinds, to get a realistic picture of its aerodynamic properties rather than a sanitised laboratory one, and found that it saved just over five watts with the vents closed compared to an average road helmet, or just under five with them open. What does that translate to? Over a 300 metre sprint at 1150 watts that would put you 1.5 metres ahead of a typical road helmet, they claim - quite possibly in first place rather than third.

That's absolutely vital if your career pivots on those 1.5 metres, as Lars Booms' does, but is perhaps not that important on the Sunday club run.

The Bell Star Pro with visor

In terms of looks, it's a bit Marmite. From certain angles it’s sleek and purposeful, from others it's reminiscent of the foam skid-lids I was made to wear as a child. The front of the helmet juts quite far forwards from the forehead, and the head-on view is rather bulbous. Ker-clunk the magnetic visor into place and it all gets a bit Sci-Fi - a coat of black spray paint and it could easily stand-in as the uniform helmet of a fascist police force in a dystopian movie universe. Frankly, it's pretty cool.

But turn up at a club run looking like that and you'd better be prepared to spend the whole morning on the front soaking up the headwind if you want to avoid ridicule. Even then, your chances are slim.

Comfort-wise it's fantastic. The adjustment doesn't just clamp tighter horizontally, but kind of pulls in and up - it's supposed to make it work for a variety of head shapes, and it seems to do the trick. The straps are nicely adjustable too, and they sit nicely around the ears rather than constantly chafing like some helmets.

All things considered, Bell's latest helmet will make you very slightly faster and considerably more space-age cool. But think of it like the bus in Speed: drop below a certain mph and it'll end badly.